Safety device for rotative sustaining means



June 19, 1951 GAZDA SAFETY DEVICE FOR ROTATIVE SUSTAINING MEANS Filed April 26, 1945 sa a Patented June 19,1951

SAFETY DEVICE FOR ROTATIVE SUSTAINING MEANS Antoine Gazda, Providence, R. I.

Application April 26, 1945, Serial No. 590,405

6 Claims.

This invention relates to a safety device for rotative sustaining means, and more particularly to a safety device for rotor blades of aircraft of the helicopter type.

It has been found that serious results may follow from the accidental rupture of rotor blades of aircraft of the helicopter type in consequence of the severe strains to which such blades are exposed when in operation. Not only does such rupture seriously impair or totally destroy the effective sustaining value of the rotor blade, but

centrifugal force due to the rotation of the blade may wholly detach the broken end of the blade and hurl it through the air.

A primary object of the present invention is the development of a novel relationship of parts in a sustaining rotor blade construction which will obviate the aforedescribed deficiencies of the prior art constructions.

To this end, briefly stated, the rotor blade is provided with means, which may preferably assume the form of ya tie, extending through the entire length of the blade, preferably through a rigid spar housing or the like. In one embodiment, the tie may be a flexible member which is subjected to tension at one end thereof. In this way, even if a break should occur in the blade .during operation thereof, the tensioned tie acts to hold the parts together in operative relationship and against undesired detachment. In a most simplified embodiment, the aforesaid means may be a simple tie member, and tensioning means may be omitted, if desired.

The foregoing and other objects and advantages of the invention which will be manifest from the detailed description hereinafter set forth, are realized by the relationship of parts according to the present improvements. The latter are illustrated, by way of presently-preferred exemplary embodiments, on the accompanying sheet of drawings, and are described in the following description.

On the sheet of drawings:

Fig. l is a fragmentary view partly in plan and partly in section of one form of construction according to the invention;

Fig. 2 is a cross-sectional view through an alternative arrangement of spar and flexible tie;

Fig. 3 is a cross-sectional view through another form of spar and flexible tie arrangement;

Fig. 4 is a cross-sectional view through still another embodiment of spar and flexible tie arrangement;

Fig. 5 is a fragmentary view, partly in section and artly in elevation through a further form of the invention, showing more particularly an arrangement of hub retention of the flexible tie;

Fig. 6 shows a modification of the form of the invention according to Fig. 5.

Fig. '7 is a fragmentary showing of a modified detail according to the invention.

Referring first to Fig. l of the drawing, reference numeral |0 designates a hollow rotor blade, the exterior of which is of conventional airfoil configuration. Blade II] is pivotally mounted, in essentially conventional forked manner, on the hinge member I! which, in turn, is threadedly mounted on threaded boss l2 projecting from the top of the sleeve |3 secured to the upper end of the hub M of the rotor blade assembly. Hub M is mounted for rotation in essentially conventional manner (not shown).

The outer end of the blade Ii! may be interiorly recessed, as shown in Fig. 1, to receive a flanged and internally threaded socket I5 secured by bolts I6 or the like. The inner end of blade I0 may be provided with a central bore extending therethrough and communicating at one end with the hollow interior of blade l0 and, at the other end, with a similar bore provided in hinge member I The latter bore terminates in an enlargement |8 substantially coextensive in diameter with the bore through sleeve l3. Secured in place in the outer end of bore I! is a flanged sleeve l9.

Extending between and supported by socket l5 and sleeve i9 is a rigid metallic cylindrical spar or blade reinforcing member 29 which may be integrated with its supports in any suitable manner. Intermediate supports for the spar 2|] may also be provided at spaced points along the length of blade Ill.

Extending through spar 2|] is a member 2| which, in the embodiment according to Fig. 1 is shown as a metallic tieof substantial diameter. The outer end of tie 2| is headed, as shown at 22, and head 22 bears against the outer surface of socket l5. The other or inner end of tie 2| is threaded and has a nut 23 screwed thereon tightly against the adjacent wall of enlargement Ill. The extreme inner end of tie 2| may be upset, after the positioning of nut 23 thereon, to provide a retaining head 24. As shown in Fig. '7 tie 2| may be maintained under spring tension by means of helical spring 25 which is positioned between nut 23 and the adjacent wall of enlargement |8 and operates to urge the nut away from the wall. The tie 2| without the spring as shown in Fig. 1 is sufliciently flexible to allow 3 some pivoting of the blade about the hinge member II.

It will be clear that, with this relationship of parts, there can be no detachment of any part of the blade in even if a rupture should accidentally occur.

In the embodiments according to Figs. 5 and 6, retention of the inner tie end is effected in the hub of the rotor blade assembly. The structure of the blades it and hinge members H in these embodiments is exactly the same as in the previously described embodiment. The tie member is somewhat modified, however, in that nut 23 and head 24 are omitted. The tie member, moreover, preferably takes the form of a flexible cable 26 which runs over a pulley 21 mountedon bracket 28, as shown, inside the hub 14. Tension on the cable is exerted, in this embodiment of the invention, by means of a piston and cylinder arrangement 29 positioned beneath the hub M. Pressure fluid may be applied for this purpose through conduit 36. Piston rod 3! terminates in a swivel joint 32, i. e. member 3.2 is mounted for relative rotation but against relative axial displacement with respect to rod 31. The end of each cable 26 .is secured tothe loop 'IOf the joint 32.

In the modification according to Fig. 6, the cable 251s maintained under tension by heavy duty spring 33 secured to plates 34 and 35 and operating to pull these two plates toward each other. Plate 351s affixed to the hub M. A loop is provided on platesfor the tying of tie members 26. It is understood, of course, that while but one tie member is shown in Figs. 5 and 6, three such tie members are provided, one for each blade.

The spar and tie member relationship may assume a wide variety of forms, several of which are shown by way of illustration in Figs. 2, 3 and 4. In Fig. 2 .'the spar member 36 is an I-bea-m, which may be secured in the hollow chamber :of blade H3 in any suitable and essentially conventional manner. Each I-beam may be associated with a pair of tie members 31 which, in contrast to tie members '2! and 26 which-are essentially circular in cross section, are shown as of square cross section. Tie members 3-! may be flexible and are secured, in suitable manner, at their respective ends to the interior of the blade tip and the tensioning means (e. g..means 33, 34,

35) if desired.

According to Fig. 3, the spar 38 is rectangular and the tie member is a flexible flat metallic strip 39. Finally, according to Fig. 4., a wire tie .25 may be housed in a triangular spar 40.

Having thus disclosed the invention, .what is claimed is:

1. Rotative sustaining means for aircraft of the helicopter type comprising a rotative .hub, a hollow rotor blade, a hinge member interconnecting said hub and blade, flexible tie means attached to the blade tip on the interior thereof and extending through to and beyond the other end of the blade, and means in said hinge member for maintaining said flexible tie means in constantly tensioned state.

2. Rotative sustaining means for aircraft of the helicopter type comprising a rotative hub, a hollow rotor blade, a hinge member interconnecting said hub and blade, flexible tie means attached to the blade tip on the interior thereof and extending through to and beyond the other end of the blade, and resilient means in said hinge member for maintaining said flexible tie means in constantly tensioned state.

3. Rotative sustaining means'for aircraft of the helicopter type comprising a rotative hub, a

hollow rotor blade, a hinge member interconnecting said hub and blade, flexible tie means attached to the blade tip on the interior thereof and extending through to and beyond the other end'of the blade, and means in said hub for main-- taining said flexible tie means in constantly tensioned state.

4. Rotative sustaining means for aircraft of the helicopter type comprising a rotative hub, a hollow rotor blade, a hinge member interconnecting .said huband .blade,. flexible tie Imeansatltached .to the blade tip on the interiorthereof and extending through to and 'beyondx thewother end of the blade, .and pressure fluid-actuated means 'for maintaining said flexible tie means in constantly tensioned'state.

5. Rotative sustainingmeans for aircraft of the helicopter type comprising hub, a hollow rotor blade, flexible tie means attachedatone end to the blade tip onthe interior thereof and extending through to and beyondthexother. end

of the blade, means in saidhub to whi'ch'the other end of said tie means is secured and means for maintaining said flexible tie means in :constantly tensioned state.

6. Rotative sustaining meansforaircraft "of the helicopter typecomprising 1a rotative hub, a hollow rotor blade, la hinge member interconmeeting said hub and blade; flexible tie means attached to the blade tip on theinterior thereof and extending through toxandbeyond the other end of the blade, and resilient means :se'curedto said hub and connected to said tie meansrfor maintaining said flexible tie means in constantly tensioned state.

:ANTOINE GAZDA.

"REFERENCES CITED The'followin'g references are of record' in the file of this patent:

UNITED "STATES TPA'I'ENTS Number Name :Date

1 ,380,057 'Gove .May. 31,1921 1,884,598 Cierva 'Oct. '25, .1932 1,922,866 Rosenberg Aug. 15. 1933 2,047,776 Hafn'er July 14, .1936 2,163A81 Cameron June 20, 1939 2,362,301 Pecker Nov. 7, .1944

FOREIGN PATENTS Number Country .Date

385,074 Great Britain :Dec. 22, .1932 

